An Israeli woman stands outside a damaged house hit by a rocket fired from the Gaza Strip that hit a house near the Israel-Gaza border, Friday, Nov. 16, 2012. Fierce clashes between Israeli forces and Gaza militants are continuing for the third day.(AP Photo/Tsafrir Abayov)

Tsafrir Abayov/AP Photo

Since Wednesday, violence has escalated in and around the Gaza Strip, resulting in the deaths of at least twenty Palestinians and three Israelis.

The region is one of many suffering from conflict near or across a border. Millions throughout history have died defending, attacking, trying to sneak across, and trying to escape these man-made, often-invisible lines. Of those, the following five are some of the most daunting.

1. Turkey-Syria Border

Syria's air force bombed a rebel-held region near the border with Turkey, killing at least one person and wounding three others, an official said. (AP Photo/AP Video)

Syria's ongoing civil war, which has caused nearly 40,000 deaths in the region, has endangered thousands in the Turkey-Syria border region in recent months. The conflict has also halted all cross-border trade, and the large influx of Syrian refugees has raised tensions in many border communities, where bombing and gunfire is commonplace. On Thursday, Turkey officially announced its recognition of the newly formed rebel coalition as the true leader of the Syrian people. Turkey's foreign minister, Ahmet Davutoglu estimated that 120,000 Syrians are residing in camps in Turkey and almost 70,000 others are living elsewhere in the country.

2. Afghanistan-Pakistan Border

Afghan women and children sit in a cart pushed by a man as they enter Afghanistan through Pakistan's border crossing in Torkham, east of Kabul, Afghanistan, Wednesday, Oct. 31, 2011. (AP Photo/Rahmat Gul)

The 1,500-mile border between these two nations is dangerous in large part because of its lawlessness. Categorized as Afghani tribal lands, the border region has provided a haven for al Qaeda militant groups fighting against the U.S. and Pakistani state. In the region, there were more than 250 drone strikes and roughly 2,000 deaths between 2004 and 2011, according to Foreign Policy magazine.

3. North Korea - South Korea Border

A North Korean defector hangs a banner wishing for reunification of the two Koreas on the wire fence at Imjingak in Paju (AP Photo/Ahn Young-joon)

The 160-mile-long border that divides North and South Korea is one of the most militarized borders in the world, with a 2.5 mile buffer zone full of heavily armed troops, missiles, and land mines, all designed to dissuade any daring border crossers. The Demilitarized Zone (aka DMZ) has been in place since 1953, the end of the Korean War, which separated the Communist, Soviet-backed North from the U.S.-backed South. Since then, North Korea has been under a rigid state-controlled system that keeps its citizens shut off from the rest of the world. The latest tensions arose in October of 2012 when South Korean activists tried to send balloons across the border carrying 200,000 leaflets critical of North Korea's authoritarian regime.